One of the most common motion simulation systems in use today are flight simulators which re-create aircraft flight and different aspects of the flight environment. Flight simulators are employed for flight training, the design and development of aircraft, control handling evaluation and other purposes. Depending on the purpose of a particular device, flight simulators can range in complexity from PC-laptop models to full flight simulators employing replicas of an aircraft cockpit including controls, aircraft systems and wide-field outside-world (OTW) visual systems all mounted on six degree-of-freedom motion platforms which move in response to control commands from the cockpit and external aerodynamic forces. These motions include three linear movements, namely heave (up and down), surge (fore and aft) and sway (side-to-side), and, three rotational movements including pitch (rotation about the sway axis), yaw (rotation about the heave axis) and roll (rotation about the surge axis).
Current full flight simulators capable of meeting the so-called Level D standard promulgated by the Federal Aviation Administration in the U.S., employ a motion platform supported by six hydraulic or electric jacks. The motion platform, in turn, mounts a vibration platform upon which the replica cockpit of the aircraft is supported. The shaft of each jack, which is extended and retracted to obtain the desired motion, has a limited degree of travel and therefore the concept of acceleration onset cuing is relied upon to provide the user of the system with the desired sensation of motion for a particular aircraft maneuver or external aerodynamic forces applied to the aircraft. Onset cuing provides an initial acceleration of the cockpit which closely replicates that of an aircraft in flight, but then the jack movement is decreased to zero after which time the motion platform is reset to a neutral position at a rate below that of the sensory threshold of the user. This technique has proven effective in simulating the six degrees-of-freedom of motion noted above. Vibration, on the other hand, which may result from rough weather, blade rotation, out-of-balance rotor, rotor gearbox malfunctions and other causes, is simulated by the vibration platform positioned between the motion platform and cockpit.
Significant limitations of current full flight simulators of the type described above include their extreme physical size and substantial cost. Typically, full flight simulators require a motion envelope of about fifty feet in width, fifty feet in length and forty feet in height, with the size of the unit itself being about twenty feet wide, twenty-five feet long and twenty-five feet in height. A huge facility is required to house such simulators, and it is challenging and expensive to install systems of such size and complexity. Further, full flight simulators typically cost between one and three million dollars (US), not including the cost of the cockpit control and OTW systems.